Duisburg, Universiẗat, Diss., 2000.

Regensburg, Universiẗat, Diss., 2001.

Zugl.: Chemnitz, Techn. Universiẗat, Diss., 2005.

Bonded copper interconnects were created using thermo-compression bonding and the dicing yield was used as an indication of the bond quality. SEM images indicated that the Cu was plastically deformed. Our experimental and modeling results indicate that the effective contact area is directly proportional to the applied load. Furthermore, for first time, results have been obtained that indicate that the dicing yield is proportional to the measured bond strength, and the bond strength is proportional to the effective contact area. It is also shown that films with rougher surfaces (and corresponding lower effective bonding areas) have lower bond strengths and dicing yields. A quantitative model for the relationship between measured surface roughness and the corresponding dicing yield has been developed. An appropriate surface-roughness data acquisition methodology has also been developed. The maximum possible applied load and the minimum possible surface roughness are required to obtain the maximum effective contact area, and hence to achieve optimum yields (both mechanically and electrically). / Singapore-MIT Alliance (SMA)

Thermocompression bonding of gold is a promising technique for achieving low temperature, wafer-level bonding without the application of an electric field or complicated pre-bond cleaning procedure. The presence of a ductile layer influences the fracture behavior of the bonds. The fabrication process was described. In addition, the effect of plasticity was explored by varying the gold bonding thickness between 0.23 to 1.4 µm. Wafers were bonded at 300°C and two different pressures: 1.25 and 7 MPa. The bond toughness of the specimens were characterized using a four-point bend delamination technique. Cohesive failure was found to be the dominant fracture mode in the thicker films. Bonds made with thin gold films failed adhesively and at lower strain energy release rates. / Singapore-MIT Alliance (SMA)

Thermocompression bonding of gold is a promising technique for the fabrication and packaging microelectronic and MEMS devices. The use of a gold interlayer and moderate temperatures and pressures results in a hermetic, electrically conductive bond. This paper documents work conducted to model the effect of patterning in causing pressure non-uniformities across the wafer and its effect on the subsequent fracture response. A finite element model was created that revealed pattern-dependent local pressure variations of more than a factor of three. This variation is consistent with experimental observations of bond quality across individual wafers A cohesive zone model was used to investigate the resulting effect of non-uniform bond quality on the fracture behavior. A good, qualitative agreement was obtained with experimental observations of the load-displacement response of bonds in fracture tests. / Singapore-MIT Alliance (SMA)

In this work the usage of a WLC (Wafer Level Camera) for ensuring road safety has been presented. A prototype of a WLC along with the Aptina MT9M114 stereoboard has been used for this project. The basic idea is to observe the movements of the driver. By doing so an understanding of whether the driver is concentrating on the road can be achieved. For this project the display of the required scene is captured with a wafer-level camera pair. Using the image pairs stereo processing is performed to obtain the real depth of the objects in the scene. Image recognition is used to separate the object from the background. This ultimately leads to just concentrating on the object which in the present context is the driver.

The usual way to remove the silicon layer is used by the solutions of HF and KOH to conduct the etching process, but those chemicals are dangerous for the humans. Therefore, this study proposes the method that uses the diamond millstone to reduce the thickness of the silicon wafer. It hopes that this method can effectively shorten the process time and reduce the amount of chemical pollution. Firstly, the effects of the working pressure, the rotating speed of the wafer, and the diamond millstone on the removing rate of silicon wafer are investigated. Then, the effect of the working pressure on the flatness of the wafer surface is investigated. Finally, the effect of the rotating speed ratio of the wafer to the diamond millstone on the track type of grinding surface is theoretically analyzed. According to the experimental results, the removing rate of silicon wafer is almost linearly proportional to the working pressure, the rotating speed of the wafer, and the diamond millstone. The lighter working pressure, the more flatness of the wafer is. According to the theoretical results, the rotating speed ratio of the wafer to the diamond millstone influences the track type of grinding surface. When this rotating speed ratio is an irrational number, the distribution of grinding track becomes finer.

No description available.

Student Number : 0312766T - MA dissertation - School of Fine Arts - Faculty of Humanities / This dissertation is primarily an investigation into the sculpture of Jeremy Wafer and specifically his oval series, Red Ovals (1995), African Forms (1996), Red Ovals (second series) (1998) and Large White Oval (2004). The aim is to establish how, from a post-structuralist and anthropomorphic position, these non-illusionistic sculptural forms may engage the viewer experientially by evoking the body visually, physically and spatially. Wafer’s reductive articulation of surface, material and form is analysed in terms of notions of secrecy and metaphorical referencing specifically relating to the human form. A ‘sense of disquiet’ is evoked by their ambiguity, and this aspect is confronted by looking at various dichotomies and their transition and hybridisation to form the ‘unifying pattern’ that Wafer’s sculptures present. The role of process, repetition and seriality are researched within this context. The works from my Simulacra exhibition in May 2005 at the Substation on the University of the Witwatersrand Campus are discussed according to the above aspects, as they are relevant to my own sculptures.